1. Field of the Invention
This invention relates to bituminous compositions and processes for their preparation and is particularly concerned with novel bituminous compositions and processes for their preparation by treatment of bitumen with a combination of an amine and an isocyanate.
2. Description of the Prior Art
Various chemical modifications of bitumen and bituminous substances have been described, which provide for particular improved properties of bitumen in specific end-use applications; see for example, U.S. Pat. Nos. 3,028,249, 3,182,032, 3,179,610, 3,615,801, 3,650,791 and British Patent Nos. 1,393,014 and 1,402,684. Thixotropic gelled bituminous cutback compositions obtained by the in-situ formation of minor amounts of a monomeric disubstituted urea in a bituminous cutback blend containing solvent, are described in U.S. Pat. No. 3,615,802.
The prior art does not disclose a simple, improved bitumen composition, which is characterized by an elevated softening range in comparison to that of the starting bitumen. Generally speaking, untreated bituminous materials, which include asphalts, tars, and pitches, regardless of the source, are characterized by their softening points. For example dead level asphalt, which is generally called a tar by those skilled in the art, has a softening range of about 53.degree. C. to 57.degree. C. as measured by the standard Ring and Ball (hereinafter R. & B.) softening point determination carried out in accordance with ASTM Test D36-26. One of the highest softening points, 81.degree. C. to 85.degree. C., is observed for a bituminous material commonly referred to as steeped asphalt.
Accordingly, in applications such as road surfaces, roof coatings, sealants, caulks and the like, in warm climates and during summer heat, these bitumens drip, run, and generally deform. In severe cases, entire road surfaces have been known to shift.
We have now found a simple, yet elegant, solution for overcoming this deficiency. The bituminous compositions made in accordance with the present invention are set forth in detail hereinbelow.